Improvement in pulley-blocks



- which turns with the axle, as hereinafter fully UNITED STATES PATENT OFFICE IMPROVEMENT lN- PULLEY-BLOCKS.

Specification forming part of Letters Patent No. 44.409, dated September 27, 1864.

To all whom it may concern:

Be it known that I, JOHN J. DoYLE, of Brooklyn, E. D., in the county of Kings and State of New York, have invented a new and Improved Anti Friction Pulley-Block; and I do hereby declare that the following is a full, clear, and exact description thereof, which will enable those skilled in the art to make and use the same, reference being had to the accompanying drawings, forming part of this specification, in whiehL Figure lis a view of my invention adjusted for use; Fig. 2, a section of one of the blocks of the same, taken in the line a' fr, Fig. 1 Fig. 3, a section of an eccentric sheave pertaining to the same, taken in the line y y, Fig. 2 5 Fig. 4, asection of Fig. 3, taken in the line z z.

Similar letters of reference indicate corresponding parts in the several figures.

The object of this invention is to obviate or remove a large portion of the friction attend-- ing the use of pulley-blocks as at present constructed, and at the same time reduce the dimensions of the block of a given power very materially, while the smallest sheave of the same will admit of the rope bending or conforming to it perfectly without the liability ot' rupturing its outer fibers. InA order to effect this result I employ an eccentric pulley, one or more, placed loosely on the axle of the block, in connection with a fast pulley, or one set forth.

A represents the cheeks of a pulley-block connected together at'suitable distances apart by rods B, as usual.

C D E represent three sheaves or pulleys, C being keyed or made fast to the axle F, D being placed loosely but concentrically upon it, and E being placed eccentrically upon the axle. The axle has its bearings in the outer cheeks, A, only. f The sheaves C D require no particular description, but the sheave E, being constructed and applied in a novel way and forming the gist of the invention, I will proceed to describe it minutely. The chief feature in this sheave E consists in its eceentricity with the axle F.

a represents a hub, provided at one side with a flange, b, which may be cast with a and c is a flange made separately and secured to the other side of the hub by screws (l. The

for the axle F to pass through, said hole in this instance being twice the diameter of the axle. (See Figs. 3 and 4.,) I

In the space or groove formed by the two anges b c there are placed a series of friction-rollers, f, which are encompassed by a ring, g, the outer surface of the latter being grooved circumferentially to receive the rope G of the block. The rope G is attached to the upper block, as shown at h, and passies around the several sheaves of the two blocks, as shown in Fig. 1. Both blocks are constructed precisely alike, and the rope Gr is arranged or applied in the usual Way.

From the above description it will be seen that the eccentric position of the sheave E is due to the increased diameter of the hole c in the hub a over the diameter of the axle F, and this eccentricity virtually diminishes the di'- amcter of said sheave to a degree equal toits eccentricity. (See Figs. 3 and 4.)

By this arrangement I obtain in a very compact way a pulley-block of a given power with sheaves of practical dimensions, for if the sheaves D E be each seven (7) inches in diameter and the pulley C ten and a half (10.12) inches, the proportion, three and one-halt', seven, ten and one-half is obtained on account ot the diameter of the sheave E being reduced by its eccentric arrangement on the axle "F, the hole c of the hub of the sheave E being twice the diameter of the portion of the axle F on which it rests.

A pulley-block could not be constructed with sheaves of the above dimensions-to wit, three and a halt', seven, ten and a halffor a strong rope would not bend or conform to the periphery of a three-and-a-half-inch pulley. Its outer fibers would rupture or break. Hence, I obtain with sheaves of a practicable size the result above specified and if the diaameter of the sheaves be enlarged, as in the old way, to obtain that proportion the block would be too large and cumbersome for practical purposes.

I would remark that the friction-rollers f Aare simply to admit of the ring g having a small compensatory movement either forward or retrograde to adjust any errors in the proper order of motion of the rope.

I would further remark. that a sheave of nine (9) inches diameter is about as small as hub a has a hole, e, made centrally through it a strong rope will bend or work over without straining or fracturing its outer rtrands; and hence a block constructed, according' to my invention, With its sheaves D E of nine (9)-inohes and the sheave C thirteen and a half (13%) inches, will bear the proportion four and onehalf, nine, thirteen and one-half, while, according to the old plan, to obtain thesame proportion the sheaves Would require to be respectively nine, eighteen, twenty'seven inches in diameter, dimensions altogetherimpracticable.

When it is required to further limit the m0- tion of an eccentric sheave, by a proportional enlargement of its eye or bore, it may be necessary in regard to the strength of materials in inner body of sheave to dispense With the use of the rope-bearing rin g g and substitute a set of concave-surfaced rollers having 'with the ordinary concentric sheaves, one or more, arranged to operate in the manner substantially as and for the purpose herein set forth.

JOHN JAMES DOYLE.

Witnesses: l

M. M. LIVINGSTON, (l. L. TOPLIFF. 

